Pump and motor



Jan. 28,1941. Jjig gg mm 2,229,115

PUMP AND MOTOR Filed Sept. 20, 1938 WITNESSES: INVENTOR:

7771135 J SB JZ flimmrmmz 1 BY U241! ATTORNEYS.

Patented Jan. 28, 1941 UNITED STATES PUMP AND MOTOR Hans 'Joseph Zimmermann, Elkins Park, Pa.

Application September 20, 1938, Serial No.230,854 In Great-Britain September 22, 1937 I iclaims. (cues-162) This invention relates to pumps of the kind in which pistons or plungers are reciprocated by means of swash plates, and it comprehends certain improvements therein having for their object a pump which is of compact formation in relation to capacity or duty; which will satisfactorily deliver liquids or gases at high pressures; which will function reliably over long periods; and, therefore, is well adapted for supplying oil under pressure to the several parts of aircraft;

which can, if desired, be self-adjusting for regulation of delivery volume against constant pressure, or, alternatively, may be regulated manually; and which is adaptable to hydraulic gears.

15 Having the aforesaid and-other objects in view, as will appear in the following specification, the invention consists in a pump-or motor, the characteristic feature of which 'is the employment of a plurality of swash plates spaced apart, and a 20 plurality of plungers intermediate the swash plates.

Various arrangements of swash plates, plungers, and driving mechanism, can be made according to the effects desired; and in a preferred 25 arrangement, two swash plates are incorporated in such a manner that they are .maintained in parallelism.

'- A pump has been suggested having two spaced kind in which two swash plates are spaced some distance apart and the plungers are arranged intermediate to the two plates in such a manner 40 that one end of each plunger is operated by thrust from one plate and the other end by thrust from the other plate, providing positive actuation on both out and return strokes, Such constructions involve stepped or two diameter 45 plungers and-annular working chambers.

In the kind of pump or motor with which this invention is more particularly concerned, the invention consists in arranging the plungers in two co-operating groups with one group in opposite 50 reciprocative phase to the other group to 'balance the axial forces within the system. In a preferred form,.the individual plungers of one group are in alternate relation to the individual plungers of the other group. Such arrangement 55 is applicable to pumps or motors of the fixed swash plate type or to those in which the angle of inclination of the plates is concurrently adjustable to vary the delivery volume.

The invention'further consists in provision for self-adjustment of the angle of the swash plates 5 by a device exposed to the pressure of the delivery 'side in order to maintain constant pressure in a communicating receiver or system.

The invention further consists in provision as aforesaid which includes a plunger having one end exposed to the delivery side, means of connection between the other end of the plunger and the swash plate or plates, and a resistance opposing the actuating movement ofthe plunger, said resistance being adjustable to enable the delivery pressure to be varied.

In order that this invention may be clearly understood and readily'carried into practice, refercnce may be had to the accompanying drawing.

Fig. I is a longitudinal section of a pump embodying thepresent improvements.

Fig. II is a staggered cross-section of the same, taken approximately as "indicated by the plane II-II in Fig. I; and,

Fig." III is a. fragmentary view of means for adjusting the resistance of the spring included in Fig.1.

Each swash plate may include two sections separated by ball or other anti-friction bearings; one indicated by I is the non-rotative section journaled at 2' in the housing 3; the other 4 for. contact with the ends of the plungers 22, 23. A suitable form for the sections I is that of a segment 'of a hollow spheroid with two integral trunnions 2 about the axis of which the swash plate may be adjusted for varying its inclination.

The driving shaft 6 serves two functions; firstly, it carries the work chambers I in an orbital path around the axis of rotation, and secondly it acts as the moving-element of a port 40 system for controlling the suction and delivery ports. With these functions in view, a number of two-diameter bores are provided in an enlargement 8 of, or part surrounding, the shaft 6; for co-operation with passages leading inwards 5 to the shaft bore, as will be later described. The plungers 22, 23, like the bores in which they slide, are of two diameters with the smaller parts ll of said plungers acting as push rods, and the larger diameter parts acting as working pistons,

The plungers 22, 23- are moved positively in both directions of reciprocation, since at one end they contact with one swatsh plate and at the other end they contact with the other swash plate, hence it will be apparent that springs are not needed for effecting the suction stroke of said plungers. Any other appropriate arrangement of passages and ports may be used for controlling the flow of liquid or gas into or from the annular working chambers,

Accordingtothe duty to which the improved pumps are to be put, the working stroke ""of the plungers 22, 23 may be fixed or variable. When the stroke is variable, the means for varying the inclination of the swash platesl may be movable by an operator, or it may be self-acting. Where the pump is required to deliver into, say a vessel or part in which constant pressure is to be maintained, the self-acting control pressure may be originated by exposing one end of a plunger l6 c to the fluid in the delivery side of the pump.

An example of such control mechanism, as depicted in Figs. I and II, comprises an auxiliary plunger |6 having one end open to the delivery port 28, and the other end in contact with a projection l8 from the non-rotatable or 'spheroid part of one of the swashplates I, to move said plates about their trunnions 2 against the resistance'of a spring l9. Conveniently, this spring IQ of thecoiled compression type is housed in the groove of a boss2|l on the other side of the casing 3, with one end of said spring abutting against a projection 2| on the trunnion-mounted part of the adjoining swash plate I, and the other end against the boss end 20. If desired, the latter end may be rendered adjustable from the exterior by the use of a shouldered screw in the end of the boss '20, Fig. III, to vary the compression eilect of the spring I9 and consequently the delivery pressure to bevaried. When the pressure in the delivery 'port 28' rises above the predetermined level, the control plunger I6 is displaced against the resistance of the spring l9 and movement communicated to the swash plates l which are turned on, their trunnions 2 to reduce the angle of inclination, the turning movement continuing until the balance of pressure is restored, if necessary to the neutral point where reciprocative motion of the plungers 22, 23 ceases. A reverse action takes place when the pressure in the delivery port 28 falls. -In

' some applications, it may be useful to carry the swash plates beyond the neutral position, the discharge then functioning as the suction, and the suction becoming the delivery.-

The two swash plates I being maintained in parallelism, the plungers 22,-23 are disposed in two groups so that one group is in opposite reciprocatlve phase to the other group, whereby the axial forces are balanced within the rotative system. Preferably, also, the units of one group are disposed in alternate relation to the units of the other group as best understood from Fig. III. Diametrically opposite plungers22 and 23 are disposed in an-axial sense, in opposition so that the push rod smaller part ,of one plunger and the larger diameter part of the other plunger 22 or 23 are in contact with the same swash plate the suction strokes are concurrent, and the delivery strokes are concurrent. Seen from the end of ends, the terms large and small having reference to the different diameters.

The distribution of pressure between two swash plates and any two diametrically-opposite plungers 22, 23 is such that the forces are balanced and the four elements can be regarded as a closed structure. The end pressure of the fluid on the working chamber 1 is similarly balanced, as the two plungers 22, 23 are moving in opposite directions at thesame time; thus the rotor is balanced. for pressure as well "as dynamically.

Adjacent plungers 22, 23 move rectilinearly in a common direction, except when passing the neutral points where reversal occurs, and thus when one is delivering, the next adjacent one is executing itssuction stroke.

An arrangement of passages and ports utilizing a central fixed stub'shaft 24 for controlling the flow of fluid, is included in Figs. I and II, wherein the enlargement 8 of the driving shaft 6 has a blindbore 2| supported rotatively on the fixed stub shaft 24; The shaft 24 has two parallel holes 25, 26 communicating at theanchored end Fig. II, for maintaining communication between i the working chambers I and the respective holes 25, 26 in the shaft 24 during the suction and delivery strokes respectively. Radial passages 3| lead from the workingchambers Ito the bore 2| of the shaft enlargement 8, 'thusforming a means of communication while traversing the cut-away portions 29,- 30 of the fixed shaft 24, but being shut off while moving over the full-diameter segments of said shaft. a I

The apparatus described is suitable for use as a pump, a compressor, or as amotor by supplying it with fluid under pressure. When constructed for operator control of the swash plates the pump shown can be run in either direction of rotation since the port control arrangements are symmetrical about the central longitudinal plane of the pump.

Having thus described my invention, I claim:

1. A pump or motor of the type described having two spaced swash plates, two-diameter plungers intermediate the swash plates, said plungers being arranged in two co-operating groups with'one group in opposite reciprocative phase to the other group, thereby to balance the axial forces. j

2. A pump or motor of the kind described having two spaced swash plates and plungers or pistons intermediate the plates, which includes a cylinder-member intermediate the plates, and two groups of plungers or pistons slidably mounted in said member, said plungers being arranged with one group in opposite'reciprocative phase to the other group, and disposed so that the plungers of one group are in'alternate relation to those of the other group."

3. In a pump or motor of the type described including a casing with suction and delivery passages, the combination of two spaced swash plates, two-diameter plungers intermediate the swash plates. said plungers arranged in two cooperating groups with one group in oppositereciprocative phase to the other group, an auxiliary plunger with one end exposed to the pres- -of said shaft by transverse ducts with registering 1 sure in the delivery passage, an abutment on one of the swash plates engaging the other end of said plunger, and a resistance means sustained intermediate an abutment on the other swash plate and an offset from the casing wall for varying the working stroke of plungers aforesaid.

4. The combination of claim 3, wherein the casing wall oifset is in the form oi a grooved boss. 

